Re: Confused about persistent connection for old clients

    Section 8.1.3 says:
    "A proxy server MUST NOT establish a persistent connection with an
    HTTP/1.0 client".
    
    Excerpt from section 19.7.1:
    "An HTTP/1.1 server may also establish persistent connections with
    HTTP/1.0 clients upon receipt of a Keep-Alive connection token."
    
    Why is there difference in handling persistent connections for proxy
    servers and for HTTP/1.1 servers?

Because it was recognized during the HTTP/1.1 design process that
the uncontrolled forwarding of HTTP/1.0 + Keep-Alive requests
through proxies (especially multiple levels of proxies) could lead
to confusing communication failures.  See the first paragraph
of 19.7.1, which explains this.

19.7.1 should perhaps say "An HTTP/1.1 origin server" where
the part that you quoted says "An HTTP/1.1 server".

-Jeff